What Is a Transaction
What Is a Transaction
Because this information is critical for business operations, it must be accurate, current, and
reliable. Data integrity would be lost if multiple programs were allowed to update the same
information simultaneously. It would also be lost if a system that failed while processing a
business transaction were to leave the affected data only partially updated. By preventing both
of these scenarios, software transactions ensure data integrity. Transactions control the
concurrent access of data by multiple programs. In the event of a system failure, transactions
make sure that after recovery the data will be in a consistent state.
program, for example, might transfer funds from a checking account to a savings account using
the steps listed in the following pseudocode:
lost. Because the steps within a transaction are a unified whole, a transaction is often defined as
an indivisible unit of work.
commits, the data modifications made by its statements are saved. If a statement within a
transaction fails, the transaction rolls back, undoing the effects of all statements in the
transaction. In the pseudocode, for example, if a disk drive were to crash during the credit